HFO-1,1,1,4,4,4-hexafluoro-2-butene, also known as HFO-1336mzz, or 1336mzz has performance properties suitable for use as a refrigerant or working fluid in applications such as air conditioning, chillers, heat pumps and organic Rankine cycles, as well as for use in foam applications. HFO-1336mzz has an ozone depletion potential of zero and low global warming potential which are desirable attributes for use as or in refrigerants and foam expansion agents.
HFO-1336mzz may exist as one of two configurational isomers, that is, the cis- or Z-isomer and the trans- or E-isomer. Processes to prepare HFO-1336mzz are known and produce a mixture of the two isomers. Each isomer has different properties, therefore, one isomer or the other may be preferred, depending on the use or application.
Because processes to produce HFO-1336mzz provide mixtures of isomers, there may be times when only one of the isomers is desired. In particular, there may be desire for only the E-isomer. Alternatively, there may be desire for only the Z-isomer.
WO 2015/059500 discloses a process to isomerize Z-1336mzz to E-1336mzz using a low sodium (less than 800 ppm) alumina based catalyst.
U.S. Pat. Nos. 8,426,655 and 8,461,401 disclose processes to prepare HFO-1336mzz starting from carbon tetrachloride and ethylene with addition of more carbon tetrachloride and HF. A mixture of 1336mzz isomers is produced. Therein, it is disclosed a preference for the cis- or Z-isomer. These patents disclose isomerizing E-1336mzz to Z-1336mzz in a vapor phase reactor using a catalyst selected from halogenated metal oxide, Lewis acid metal halides and zero valent metals.
There continues to be value to produce E-HFO-1336mzz.